Millwall Football Club is not exactly a glamorous club to support. They play inside a half-empty stadium that is indiscernible among an industrial cluster of buildings sited in a dank corner of South London.

The football’s not great, either; the club has languished in the lower tiers of the English Football League for nearly 30 years. There are lots of reasons for this. The club’s reputation for hooliganism and its high ticket prices are part of the problem, but digging deeper into the numbers, it appears that the team’s poor performance is key.

The Lions’ attendance took a turn for the worse after the club were relegated from the Championship to League One in 2015. Since 1990 – when they were relegated from the old First Division – the club’s average attendance has not exceeded 14,000, around two thirds of their 20,146 capacity.

During the same period, Millwall’s League One counterparts and South London rivals Charlton Athletic, however, have managed to attract an average of over 20,000 fans to the Valley since 2006.

George Lampey, member of the Millwall Supporters Club, and one of the hosts of Lions Radio, says: “If we were in the Championship, our crowds would improve. And of course if we were in the Premiership, then we wouldn’t have to worry about any spaces being available.”

This graph below shows how Millwall’s attendance has fluctuated since that relegation. From the 2000/01 to 2005/06 season, Millwall’s attendance picks up after they reach the second tier of the Football League. It drops off again following relegation to the third tier in 2006, but then rises again during their spell in the second tier between 2010-2015. Finally, from 2015 to the present, it dips after they were relegated back to the third tier in 2015.

If Millwall is your team, take our quiz to find out if you are a loyal supporter or a fickle fan.

This is part of our series Lost Lions: where are Millwall’s fans? Tomorrow, we visit the Den on match day to explore what Millwall are doing to attract fans and how they are giving back to the community.